This section introduces aspects that may be helpful in facilitating a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Conventional communication systems mostly comprise a backbone part and an access part. For example, a wireless communication network may comprise a Radio Access Network (RAN) part, which establishes and controls wireless access, and a Core Network (CN), through which other networks and other users of the wireless communication network are connected. Another example of a packet data or a packet switched communication network is the communication network established between the servers and routers of the World Wide Web (WWW). With the steady increases of data demand, interfaces and networks are improved to handle the increased load. For wired connections in the network, optical data transmission using fibers is used to enhance the link capacity between such interfaces.
In communications systems, such as systems using optical data transmission, wireless, wireline or powerline communications, digital data values may be transmitted by means of an optical transmission signal. The optical transmission signal is generated by modulating the phase and/or the amplitude of an optical carrier signal, which possesses a carrier frequency, in dependence on the transmitted data values and in accordance with a constellation diagram of a respective Phase-Shift Keying (PSK) modulation or Quadrature Amplitude Modulation (QAM) method. Prominent examples are Binary Phase Shift Keying (BPSK), Quaternary Phase Shift Keying (QPSK), 16 QAM, 64 QAM, etc.
In optical receivers, components, such as, for example, Analog-to-Digital (AD) converters, Digital Signal Processors (DSPs), filter structures, for example, butterfly equalizers, etc., comply with a sampling rate applied to digitize an Optical-to-Electrical (OE) converted signal. For example, a sampling rate of 2 samples per symbol may be used for these components. Generally, the higher the sampling rate the higher an operating frequency of respective processing components and the higher a power consumption of these respective components.
Document US 2011/0236025 A1 describes an apparatus and methods for optimizing the interplay between the sampling rate of an ADC of a receiver system and a bandwidth of analog anti-aliasing filters. The described technology can be used to mitigate aliasing for receiver systems that operate at fractional sampling rates by optimizing a bandwidth of optical and electrical filters included in the receiver systems.